Low flow rate measurement and control

Abstract

A turbine wheel flow measuring transducer located in a fluid receiving chamber is provided for measuring low flow rates of fluids, whether liquids, gases, or mixtures, and in controlling the fluid flow rates. The transducer is in the form of a small diameter turbine wheel having a plurality of semi-circular lateral openings in its outer periphery. The openings are sequentially presented to the incoming fluid into the chamber and the turbine wheel rotates according to the fluid flow rate. Measuring and controlling of fluid flow rates as low as 4-5 milliliters per minute and as high as 100 milliliters per minute is permitted.

1. A flow meter for a fluid flowing at a low flow rate, comprising:
 a housing body; 
 a flow inlet in the housing body receiving incoming fluid at the low flow rate; 
 a flow outlet in the housing body allowing the fluid to exit from the housing body; 
 a flow receiving chamber located in the housing body between the flow inlet and the flow outlet and receiving the low flow rate fluid; 
 a turbine wheel mounted for rotational movement within the flow receiving chamber, the turbine wheel having a plurality of semi-circular openings formed therein at spaced positions about an outer peripheral portion, the openings extending laterally through the turbine wheel; 
 the openings being successively positioned adjacent the flow inlet as the turbine wheel rotates and defining a volumetric space receiving a quantity of the incoming low flow rate fluid from the flow inlet; and 
 a monitoring mechanism for monitoring the rotation of the turbine wheel in response to the passage of the low flow rate fluid through the receiving chamber. 
 
   
   
     2. The flow controller of  claim 1 , wherein the plurality of semi-circular openings formed in the turbine wheel are located at equally spaced radial positions about the outer peripheral portion of the turbine wheel, the walls of the semi-circular openings in the turbine wheel forming blades moving in response to the energy of the fluid entering the flow chamber at the flow inlet. 
   
   
     3. The flow controller of  claim 2 , wherein the diameter of the turbine wheel is from about 0.4 inches to about 0.6 inches and the plurality of semi-circular grooves have a diameter of about one-fourth the diameter of the turbine wheel. 
   
   
     4. The flow controller of  claim 3 , wherein the turbine wheel is formed substantially of 10 percent graphite filled polytetrafluorethylene. 
   
   
     5. The flow controller of  claim 4 , wherein the turbine wheel further includes an axis on which the turbine wheel rotates, the axis having an axis width of about 0.09 inches to about 0.11 inches and the turbine wheel having a width less than the axis width. 
   
   
     6. The flow controller of  claim 1 , wherein the openings in the turbine wheel form an arc extending inwardly from an outer circumferential surface of the turbine wheel. 
   
   
     7. The flow controller of  claim 6 , wherein the openings form a semi-circular arc. 
   
   
     8. The flow controller of  claim 6 , wherein the openings form an arc of from about 150° to about 210°. 
   
   
     9. The flow controller of  claim 6 , wherein the openings form an arc of about 180°. 
   
   
     10. A turbine wheel mounted for rotational movement within a flow receiving chamber, the turbine wheel having a plurality of semi-circular openings formed therein at spaced positions about an outer peripheral portion, the openings extending laterally through the turbine wheel; the openings being successively positioned adjacent the flow inlet as the turbine wheel rotates and defining a volumetric space receiving a quantity of an incoming low flow rate fluid from the flow inlet. 
   
   
     11. The turbine wheel of  claim 10 , wherein the openings in the turbine wheel form an arc extending inwardly from an outer circumferential surface of the turbine wheel. 
   
   
     12. The turbine wheel of  claim 11 , wherein the openings form a semi-circular arc. 
   
   
     13. The turbine wheel of  claim 11 , wherein the openings form on arc of from about 150° to about 210°. 
   
   
     14. The turbine wheel of  claim 11 , wherein the openings form on arc of about 180°. 
   
   
     15. The turbine wheel of  claim 10 , wherein the plurality of semi-circular openings formed in the turbine wheel are located at equally spaced radial positions about the outer peripheral portion of the turbine wheel, the walls of the semi-circular openings in the turbine wheel forming blades moving in response to the energy of the fluid entering the flow chamber at the flow inlet. 
   
   
     16. The improved system of  claim 15 , wherein the diameter of the turbine wheel is from about 0.4 inches to about 0.6 inches and the plurality of semi-circular grooves have a diameter of about one-fourth the diameter of the turbine wheel. 
   
   
     17. The improved system of  claim 16 , wherein the turbine wheel is formed substantially of 10 percent graphite filled polytetrafluorethylene. 
   
   
     18. A flow controller for controlling the rate of a fluid flowing at a low flow rate through a fluid conduit, comprising:
 a flow meter, comprising:
 a housing body; 
 a flow inlet in the housing body receiving incoming fluid at the low flow rate; 
 a flow outlet in the housing body allowing the fluid to exit from the housing body; 
 a flow receiving chamber located in the housing body between the flow inlet and the flow outlet and receiving the low flow rate fluid; 
 a turbine wheel mounted for rotational movement within the flow receiving chamber, the turbine wheel having a plurality of semi-circular openings formed therein at spaced positions about an outer peripheral portion, the openings extending laterally through the turbine wheel; 
 the openings being successively positioned adjacent the flow inlet as the turbine wheel rotates and defining a volumetric space receiving a quantity of the incoming low flow rate fluid from the flow inlet; and 
 a monitoring mechanism for monitoring the rotation of the turbine wheel in response to the passage of the low flow rate fluid through the receiving chamber; and 
 
 a valve located in the conduit and operably connected to the flow meter to adjust the rate of flow through the conduit based on the measured flow rate. 
 
   
   
     19. The flow controller of  claim 18 , wherein the openings in the turbine wheel form an arc extending inwardly from an outer circumferential surface of the turbine wheel. 
   
   
     20. The flow controller of  claim 18 , wherein the openings form a semi-circular arc. 
   
   
     21. The flow controller of  claim 18 , wherein the openings form on arc of from about 150° to about 210°. 
   
   
     22. The flow controller of  claim 18 , wherein the openings form on arc of about 180°.